Zurich Airport to Lucerne

I will be arriving in Zurich on 5 June 2013 and has to proceed on to Lucerne. I have bought the 8days Swiss Pass which I intend to use starting 8 June 2013 for the longer journeys. That being so, I intend to buy the normal train ticket from Zurich-Lucerne. Do I take the SBB trains or are there any other railways I should consider ? Should I buy the tickets online or should I just buy it at the station on the day I arrive ? Since I am arriving at about 8am, how much time do I need to clear the immigration, get my luggages and get to the train platform to board the train so I can estimate the departure time of the train ticket that I should be buying ?

You don't need seat reservations in Switzerland; your ticket is valid for any train from Zurich to Lucerne on the date printed on the ticket. You can get your ticket online or at the rail station. You'd just take any train you find in the timetable. Tickets are valid for all train operators.